Substrate processing apparatus

ABSTRACT

A method and apparatus capable of eliminating occurrence of a development failure when a DI water discharge nozzle  20  is scanned to dry a substrate by spinning. A substrate is held in a horizontal posture by a spin chuck and rotated about a vertical axis by a rotation motor, and when an outlet of the nozzle is scanned from a position opposed to a center of the substrate W to a position opposed to a circumferential edge while a cleaning solution being discharged, immediately after the nozzle has started to move, only one dried core is produced in the vicinity of the center of the substrate, and thus production of not less than two dried cores in the vicinity of the center of the substrate is prevented. The dried region is spread all over the surface of the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing method and asubstrate processing apparatus in which a substrate such assemiconductor wafer, liquid crystal display glass substrate, photo-maskglass substrate, optical disk substrate is rotated about a vertical axisin a horizontal plane, and the substrate is dried while feeding acleaning solution such as de-ionized water onto the surface of thesubstrate.

2. Description of the Related Art

In a conventional process of manufacturing a semiconductor device, acircuit pattern is formed on a resist film of a substrate employing alithography, for example, by the steps of applying a photo-resist on asilicone substrate, printing a circuit pattern onto a resist film on thesubstrate using an exposure device, and developing the resist filmhaving been exposed with a developer. In the developing among thesesteps, the developer is fed onto the resist film having been exposed andformed on the surface of the substrate, for example, with the use of aslit nozzle, and thereafter, while the substrate is being rotated aboutthe vertical axis in a horizontal plane, a cleaning solution (rinse)such as DI water is discharged on the center of the substrate from anoutlet of the straight nozzle. The cleaning solution having been fed onthe center of the substrate diffuses toward a circumferential edge ofthe substrate by a centrifugal force to spread all over the substrate,and washes out the developer from the resist film on the substratesurface. When this cleaning (rinsing) is ended, the feed of a cleaningsolution from the nozzle onto the substrate is stopped, thereafter thenumber of revolutions of the substrate is further increased, and thusthe cleaning solution on the resist film on the substrate surface isshaken off by the centrifugal force, whereby the substrate is dried (byspinning).

When the substrate is dried by spinning as mentioned above, however, adroplet of the cleaning solution may remain forming a spot on thesubstrate occurs. This is because, on the substrate having beenprocessed, hydrophilic portions and hydrophobic portions coexist on thesurface of the resist film, thereby leading to fluctuations in retentionof the cleaning solution on the substrate. It is known that the dropletof the cleaning solution having remained as a spot on the resist patternof the surface of the substrate like this is a factor of causing adevelopment failure.

To overcome the above-mentioned problems, a method (so-called scanrinsing) has been proposed, and in which in the process of drying asubstrate, while a cleaning solution is being discharged from an outletof a cleaning solution discharge nozzle, the outlet of this dischargenozzle is scanned from the center of the substrate to the peripherythereof. In this method, since the drying goes on keeping a state thatdroplets of the cleaning solution are formed and held from the center ofthe substrate to the circumferential edge, the droplet of the cleaningsolution is less likely to remain on the substrate, in spite of a resistfilm surface on which hydrophilic portions and hydrophobic portions aremixed. A further method has been proposed, and in which at the time ofscanning a discharge nozzle of the cleaning solution while the cleaningsolution is being discharged from the outlet of the discharge nozzle,with a gas blown out from an air jet nozzle, the air jet nozzle is movedfrom the center of the substrate toward the periphery together or insynchronization with the cleaning solution discharge nozzle (forexample, refer to the Japanese Patent No. 3694641)

In the above-mentioned scan rinsing, as compared with a conventionalspin drying, the development failure maybe largely reduced. In the case,however, where the method of scan rinsing is applied to a substrateincluding a resist film surface of high water-repellent properties (forexample, a contact angle of water is not less than 60°), it is foundthat the development failure occurs showing the following phenomenon.

That is, when the discharge nozzle is scanned from the center of thesubstrate toward the periphery while the cleaning solution is beingdischarged from the outlet of the cleaning solution discharge nozzle,first the entire surface of the substrate W is covered with a liquidfilm 3 of the cleaning solution, as illustrated in a plan view of thesubstrate of FIG. 7A, and subsequently the liquid film 3 in the centerportion of the substrate W comes to be thinner to be brought in a stateof just before being dried. Then, a portion 4 in the state of justbefore being dried indicated by a two-dot chain line (hereinafter,referred to as “portion just before being dried”), is spread outward bydegrees as illustrated in FIG. 7B, and a dried core 5 a is produced inthe portion 4 just before being dried. This dried core 5 a is enlargedto form a dried region 6 a. This dried region 6 a is spread all over thesurface of the substrate W to dry the substrate W. However, in the casewhere the resist film surface on the substrate has high water-repellentproperties, in the vicinity of the center of the substrate W, a seconddried core 5 b is produced following the production of the first driedcore 5 a within the portion 4 just before being dried, and there aresome cases where a further new dried core is produced. Moreover, in theprior art, the discharge nozzle is merely moved from the center of thesubstrate W toward the periphery, so that a comparatively wide portion 4just before being dried is formed in the vicinity of the center of thesubstrate W. Therefore, in the vicinity of the center of the substrateW, the second dried core 5 b is produced in the portion 4 just beforebeing dried, and sometimes a further new dried core is produced.Incidentally, no dried core is produced other than in the vicinity ofthe center of the substrate W. Then, as illustrated in FIG. 7C, thedried region 6 a having been first formed is enlarged, and the seconddried core 5 b is enlarged to form a second dried region 6 b, and thisdried region 6 b is enlarged as well.

The two dried regions 6 a and 6 b are enlarged respectively as mentionedabove, and the two dried regions 6 a and 6 b are collided each other tobe joined, as illustrated in FIG. 7D. Then, one dried region 6 c isproduced as illustrated in FIG. 7E. At this time, a droplet 7 of thecleaning solution is produced at a boundary portion between two driedregions 6 a and 6 b. Subsequently, although the dried region 6 c that isformed by being joined into one is enlarged to the outside asillustrated in FIG. 7F, the droplet 7 of the cleaning solution remainsas it is to the end. Then, although finally the entire surface of thesubstrate W will be dried as illustrated in FIG. 7G, the remainingdroplet 7 of the cleaning solution will be dried as it is, and a driedmark (stain such as a water mark) 7′ of the cleaning solution remains asit is on the substrate W. As a result, a development failure will occur.Incidentally, the phenomenon as mentioned above is not limited to thecase of drying by scan rinsing a substrate having been processed, but isfound to happen generally in the case of a substrate having a surface ofhigh water-repellent properties.

Additionally, according to the method described in the above-mentionedJapanese Patent No, 3694641, while an air jet nozzle that is disposedspaced apart by a predetermined distance from a cleaning solution(rinse) discharge nozzle is being moved from the center of the substrateto the periphery integrally or in synchronization with the cleaningsolution discharge nozzle, a gas is blown out from the air jet nozzle,thereby the cleaning solution remaining on the substrate is dried andremoved. By this method, however, the production of not less than twodried cores in the vicinity of the center of the substrate cannot beprevented. Moreover, when two dried cores are produced in the vicinityof the center of the substrate, even if the gas is blown to thesubstrate from the air jet nozzle, there is such occurrence asrespective dried cores are enlarged ant thus the dried regions arespread, and then the two dried regions are collided each other to bejoined into one. Consequently, a problem exists in that the productionof dried marks of the cleaning solution that will be the cause of thedevelopment failure cannot be eliminated.

SUMMARY OF THE INVENTION

The present invention was made in view of the situations mentionedabove, and has an object of providing a substrate processing methodcapable of eliminating the occurrence of, e.g., development failure whenwith a cleaning solution being discharged from an outlet of a dischargenozzle to a surface of a substrate, the outlet thereof is scanned from acenter of the substrate to a circumferential edge, to dry the substrateby spinning. The invention also provides a substrate processingapparatus by which the substrate processing method can be preferablycarried out.

The invention according to one aspect is a substrate processing methodin which a substrate is held in a horizontal posture and rotated about avertical axis, and while a cleaning solution is being discharged to asurface of the substrate from an outlet of a discharge nozzle, theoutlet of the mentioned discharge nozzle is scanned from a positionopposed to a center of the substrate to a position opposed to acircumferential edge of the substrate, to dry the substrate; and inwhich only one dried core, which will be a starting point when a driedregion is formed, is produced on the substrate being in a state that thesurface thereof is covered with the cleaning solution, and then thedried region letting this dried core be a starting point is spread allover the surface of the substrate, to dry the substrate.

According to this substrate processing method, one dried region, lettingonly one dried core produced in the vicinity of the center of thesubstrate be a starting point, is spread all over the substrate to drythe substrate, and there is no production of not less than two driedcores in the vicinity of the center of the substrate. Consequently,there is no occurrence of remaining dried marks of a cleaning solutionon the substrate. As a result, the occurrence of, e.g., developmentfailure can be eliminated.

According to another aspect of the invention, the outlet of thementioned discharge nozzle is started to move from the position opposedto the center of the substrate toward the circumferential edge of thesubstrate, and in a region inside a circumference letting a centerposition of the substrate be a center and letting a distance to aposition on the substrate surface opposed to the outlet of the mentioneddischarge nozzle be a radius, after a first dried core that will be astarting point at the time when a dried region is formed on thesubstrate has been produced, before a second dried core is produced, agas is blown out to the center surface of the substrate from a jet holeof a gas jet nozzle.

According to this substrate processing method, after the outlet of thedischarge nozzle has started to move from the position opposed to thecenter of the substrate toward the circumferential edge of thesubstrate, and after the first dried core has been produced in thevicinity of the center of the substrate, before the second dried core isproduced, a gas is blown out to the center surface of the substrate fromthe jet hole of the gas jet nozzle. Accordingly, before the second driedcore is allowed to be produced, one dried region is forced to formrapidly letting the first dried core be a starting point, and this onedried region spreads toward the outside, to dry the entire surface ofthe substrate. In this manner, one dried region letting one dried corehaving been produced in the vicinity of the center of the substrate be astarting point spreads all over the surface of the substrate to dry thesubstrate, and there is no production of not less than two dried coresin the vicinity of the center of the substrate, so that there is nooccurrence of remaining dried marks of any cleaning solution on thesubstrate. These operations are now described in further detail withreference to FIGS. 3 illustrating plan views of the substrate.

While a cleaning solution is being discharged from the outlet of thecleaning solution discharge nozzle indicated by reference numeral 1, thedischarge nozzle 1 is moved from the center of the substrate W to theperiphery, and when a short time period has elapsed since the start ofthe discharge nozzle 1 being moved and the discharge nozzle 1 has movedto a predetermined position, a gas is blown out toward the centersurface of the substrate W from the jet hole of the gas jet nozzle 2 asillustrated in FIG. 3B. At this time, although first the entire surfaceof the substrate W is covered with a liquid film 3 of the cleaningsolution, the liquid film 3 in the vicinity of the center of thesubstrate W comes to be thinner to be in a state of just before beingdried, and subsequently, a first dried core 5 is produced in a portion 4just before being dried indicated by the two-dot chain line, asillustrated in FIG. 3A. Then, at the right time after the first driedcore 5 has been produced and before the second dried core is produced,the gas is blown out to the center surface of the substrate W from thejet hole of the gas jet nozzle 2, whereby without production of thesecond dried core in the vicinity of the center of the substrate W, thefirst dried core 5 is enlarged to form a dried region 6, as illustratedin FIG. 3B. At this time, on the outside of a circumference letting thecenter of the substrate W be a center and letting a distance to theposition on the substrate surface opposed to the outlet of the dischargenozzle 1 be a radius, since a cleaning solution continues to bedischarged from the outlet of the discharge nozzle 1, the liquid film 3remains as it is. Then, accompanied by the movement of the dischargenozzle 1 toward the circumferential edge of the substrate W, the firstdried region 6 spreads outward as illustrated in FIGS. 3C and 3D, andthe dried region 6 spreads all over the surface of the substrate W todry the substrate W as illustrated in FIG. 3E.

According to this substrate processing method, there is no occurrence ofsuch a phenomenon that not less than two dried cores are produced in thevicinity of the center of the substrate and not less than two driedregions are collided each other to be joined, so that there are no driedmark of the cleaning solution remaining on the substrate. As a result,the occurrence of, e.g., development failure can be eliminated.

According to another aspect of the invention, a gas of a large flow rateis instantaneously blown out toward the center surface of the substratefrom the jet hole of the mentioned gas jet nozzle.

According to this substrate processing method, due to that a gas of alarge flow rate is instantaneously blown out toward the center surfaceof the substrate from the jet hole of the gas jet nozzle, in thevicinity of the center of the substrate, one dried region is formed atonce letting the first dried core be a starting point.

According to another aspect of the invention, a gas of a small flow rateis continuously blown out toward the center surface of the substratefrom the jet hole of the mentioned gas jet nozzle.

According to this substrate processing method, due to that a gas of asmall flow rate is continuously blown out toward the center surface ofthe substrate from the jet hole of the gas jet nozzle, in the vicinityof the center of the substrate, one dried region is formed letting thefirst dried core be a starting point, and this dried region spreadsoutward.

According to another aspect of the invention, after the outlet ofmentioned discharge nozzle has started to move from the position opposedto the center of the substrate toward the circumferential edge of thesubstrate, before drying is started at the center portion of thesubstrate, the outlet of the mentioned discharge nozzle is once stopped,and after drying has started in a small region inside a circumferenceletting a center position of the substrate be a center and letting adistance to a position on the substrate surface opposed to the outlet ofthe mentioned discharge nozzle be a radius, the outlet of the mentioneddischarge nozzle is moved again toward the circumferential edge of thesubstrate.

According to this substrate processing method, after the outlet of thedischarge nozzle has started to move from the position opposed to thecenter of the substrate toward the circumferential edge of thesubstrate, the outlet of the discharge nozzle is once stopped. By thisoperation, the area of the portion just before being dried in thevicinity of the center of the substrate is controlled, and thus theproduction of not less than two dried cores in the vicinity of thecenter of the substrate can be prevented. Then, the first core isproduced in the vicinity of the center of the substrate, this dried coreis enlarged, and then after drying has started in a small region lettingthe center position of the substrate be a center and letting a distanceto the position on the substrate surface opposed to the outlet of thedischarge nozzle be a radius, the outlet of the discharge nozzle ismoved again toward the circumferential edge of the substrate. As aresult, one dried region spreads outward, and the entire surface of thesubstrate is dried. In this manner, only one dried core is produced inthe vicinity of the center of the substrate, and thus one dried regionletting this dried core be a starting point spreads all over the surfaceof the substrate, so that there is no occurrence of such a phenomenonthat dried marks of a cleaning solution remain on the substrate. Theseoperations are described in further detail with reference to FIGS. 6illustrating plan views of the substrate.

While the cleaning solution is being discharged from the outlet of thecleaning solution discharge nozzle indicated by reference numeral 1, thedischarge nozzle 1 is moved from the center of the substrate W towardthe periphery, and when the discharge nozzle 1 has moved to apredetermined position, the discharge nozzle 1 is once stopped whilecontinuing to discharge the cleaning solution from the outlet. At thistime, although first the entire surface of the substrate W is coveredwith the liquid film 3 as illustrated in FIG. 6A, the liquid film 3comes to be thinner in a small region letting the center position of thesubstrate be a center and letting a distance to the position on thesubstrate surface opposed to the outlet of the discharge nozzle 1 be aradius, to come into a state of just before being dried. Subsequently,one dried core 5 is produced in a portion 4 just before being driedindicated by the two-dot chain line, and the dried core 5 is enlarged toform a dried region 6 as illustrated in FIG. 6B. At this time, on theoutside of the mentioned circumference, since the cleaning solutioncontinues to be discharged from the outlet of the discharge nozzle 1,the liquid film 3 remains as it is. Then, by controlling the area of theportion 4 just before being dried inside of the mentioned circumferencewith a stop position of the discharge nozzle 1, the production of notless than two dried cores in the vicinity of the center of the substrateW is prevented.

When drying of the substrate W is started in the small region inside thementioned circumference, the discharge nozzle 1 is moved again towardthe circumferential edge of the substrate W. Thus, one dried region 6spreads outward as illustrated in FIGS. 6C and 6D, and the dried region6 spreads all over the surface of the substrate W to dry the substrate Was illustrated in FIG. 6E.

According to this substrate processing method, there is no occurrence ofsuch a phenomenon that not less than two dried cores are produced in thevicinity of the center of the substrate and not less than two driedregions are collided each other to be joined, so that there is nooccurrence of remaining dried marks of the cleaning solution on thesubstrate. As a result, the occurrence of, e.g., development failure canbe eliminated.

According to another aspect of the invention, after the outlet ofmentioned discharge nozzle has started to move from the position opposedto the center of the substrate toward the circumferential edge of thesubstrate, a drying gas is blown out to the center surface of thesubstrate from the jet hole of the gas jet nozzle.

According to this substrate processing method, due to that after theoutlet of the discharge nozzle has started to move from the positionopposed to the center of the substrate toward the circumferential edgeof the substrate, a drying gas is blown out to the center surface of thesubstrate from the jet hole of the gas jet nozzle, drying is rapidlystarted in a small region letting the center position of the substratebe a center and letting a distance to the position on the substratesurface opposed to the outlet of the discharge nozzle having been oncestopped be a radius, thus enabling to shorten a time period of oncestopping the discharge nozzle. As a result, a throughput can beimproved.

The invention according to a further aspect is a substrate processingapparatus comprising: substrate holding means holding a substrate in ahorizontal posture; substrate rotating means rotating the substrate heldby the mentioned substrate holding means about a vertical axis; adischarge nozzle discharging a cleaning solution from an outlet to asurface of the substrate that is held by the mentioned substrate holdingmeans and rotated by the mentioned substrate rotating means; cleaningsolution feeding means feeding the cleaning solution to this dischargenozzle; and nozzle moving means scanning the outlet of the mentioneddischarge nozzle from a position opposed to a center of the substrate toa position opposed to a circumferential edge of the substrate while thecleaning solution is being discharged onto the surface of the substratefrom the mentioned outlet. This substrate processing apparatus furthercomprises: a gas jet nozzle blowing out a gas toward a center surface ofthe substrate from a jet hole thereof in a state that the jet hole isstopped at a position opposed to the center of the substrate; gasfeeding means feeding a gas to the mentioned gas jet nozzle; and controlmeans controlling the mentioned gas feeding means such that immediatelyafter the outlet of the mentioned discharge nozzle has started to movefrom the position opposed to the center of the substrate toward thecircumferential edge of the substrate, the gas is blown out toward thecenter surface of the substrate from the jet hole of the mentioned gasjet nozzle.

In this substrate processing apparatus, the gas feeding means iscontrolled by the control means, and immediately after the outlet of thedischarge nozzle has started to move from the position opposed to thecenter of the substrate toward the circumferential edge of thesubstrate, the gas is blown out to the center surface of the substratefrom the jet hole of the gas jet nozzle. Accordingly, before the seconddried core is allowed to be produced, one dried region is forced to formrapidly letting the first dried core be a starting point, and this onedried region spreads toward to the outside, to dry the entire surface ofthe substrate. In this manner, one dried region letting only one driedcore having been produced in the vicinity of the center of the substratebe a starting point spreads all over the surface of the substrate to drythe substrate, and there is no production of not less than two driedcores in the vicinity of the center of the substrate, so that there isno occurrence of remaining dried marks of a cleaning solution on thesubstrate. As a result, when using this substrate processing apparatus,the substrate processing method as described above is preferably carriedout, thus enabling to provide the above-mentioned advantages.

According to another aspect of the invention, the mentioned controlmeans controls the mentioned gas feeding means such that a gas of alarge flow rate is instantaneously blown out toward the center surfaceof the substrate from the jet hole of mentioned gas jet nozzle.

In this substrate processing apparatus, the gas feeding means iscontrolled by control means, and thus the gas of a large flow rate isinstantaneously blown out toward the center surface of the substratefrom the jet hole of the gas jet nozzle. Accordingly, in the vicinity ofthe center of the substrate, one dried region is formed at once lettingthe first dried core be a starting point. As a result, when using thissubstrate processing apparatus, the substrate processing method asdescribed above is preferably carried out, thus enabling to provide theabove-mentioned advantages.

According to another aspect of the invention, the mentioned controlmeans controls the mentioned gas feeding means such that a gas of asmall flow rate is continuously blown out toward the center surface ofthe substrate.

In this substrate processing apparatus, the gas feeding means iscontrolled by control means, and thus the gas of a small flow rate iscontinuously blown out toward the center surface of the substrate fromthe jet hole of the gas jet nozzle. Accordingly, in the vicinity of thecenter of the substrate, one dried region is formed letting the firstdried core be a starting point, and thus this dried region spreadsoutward. As a result, when using this substrate processing apparatus,the substrate processing method is preferably carried out as describedabove, thus enabling to provide the above-mentioned advantages.

The invention according to yet another aspect is a substrate processingapparatus comprising: substrate holding means holding a substrate in ahorizontal posture; substrate rotating means rotating the substrate heldby the mentioned substrate holding means about a vertical axis; adischarge nozzle discharging a cleaning solution from an outlet to asurface of the substrate that is held by the mentioned substrate holdingmeans and rotated by the mentioned substrate rotating means; cleaningsolution feeding means feeding the cleaning solution to the mentioneddischarge nozzle; and nozzle moving means scanning the outlet of thementioned discharge nozzle from a position opposed to a center of thesubstrate to a position opposed to a circumferential edge of thesubstrate while the cleaning solution is being discharged onto thesurface of the substrate from the mentioned outlet. This substrateprocessing apparatus further comprises: control means controlling thementioned nozzle moving means such that after the outlet of thementioned discharge nozzle has started to move from a position opposedto a center of the substrate toward a circumferential edge of thesubstrate, before drying at the center portion of the substrate isstarted, the outlet of the mentioned discharge nozzle is once stopped,and after drying has started in a small region letting a center positionof the substrate be a center and letting a distance to a position on thesubstrate surface opposed to the outlet of mentioned discharge nozzle bea radius, the outlet of the mentioned discharge nozzle is moved againtoward the circumferential edge of the substrate.

In this substrate processing apparatus, the nozzle moving means iscontrolled by control means, and after the outlet of the dischargenozzle has started to move from the position opposed to the center ofthe substrate toward the circumferential edge of the substrate, theoutlet of the discharge nozzle is once stopped. By this operation, thearea of the portion just before being dried in the vicinity of thecenter of the substrate is controlled, and thus the production of notless than two dried cores in the vicinity of the center of the substratecan be prevented. Furthermore, one dried core is produced in thevicinity of the center of the substrate, this dried core is enlarged,and after drying has started in a small region letting the centerposition of the substrate be a center and letting a distance to theposition on the substrate surface opposed to the outlet of the dischargenozzle be a radius, the nozzle moving means is controlled by controlmeans, and then the outlet of the discharge nozzle is made to move againtoward the circumferential edge of the substrate. Accordingly, one driedregion spreads outward, and the entire surface of the substrate isdried. In this manner, only one dried core is produced in the vicinityof the center of the substrate, and one dried region with this driedcore a starting point spreads all over the surface of the substrate todry the substrate, so that there is no occurrence of such a phenomenonthat dried marks of the cleaning solution remain on the substrate. As aresult, when using this substrate processing apparatus, the substrateprocessing method as described above in paragraph [0015] is preferablycarried out, thus enabling to provide the above-mentioned effects.

According to another aspect of the invention, the substrate processingapparatus further comprises: a gas jet nozzle blowing out a drying gasfrom a jet hole to the center surface of the substrate that is held bythe mentioned substrate holding means and rotated by the mentionedsubstrate rotating means; and gas feeding means feeding a drying gas tothis gas jet nozzle.

In this substrate processing apparatus, after the outlet of thedischarge nozzle has started to move from the position opposed to thecenter of the substrate toward the circumferential edge of thesubstrate, a drying gas is fed to the gas jet nozzle by gas feedingmeans, and thus the drying gas is blown out to the center surface fromthe jet hole of the gas jet nozzle, whereby drying is rapidly started ina small region letting the center position of the substrate be a centerand letting a distance to the position on the substrate surface opposedto the outlet of the discharge nozzle be a radius. As a result, whenusing this substrate processing apparatus, the substrate processingmethod as described above is preferably carried out, thus enabling toprovide the above-mentioned advantages.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view illustrating one example of constructionof a substrate processing apparatus used in carrying out a substrateprocessing method according to the present invention.

FIG. 2 is a schematic sectional view of the substrate processingapparatus illustrated in FIG. 1.

FIGS. 3A-3E are views for explaining operations in the substrateprocessing method according to the invention, and are plan views eachillustrating a substrate.

FIG. 4 is a schematic plan view illustrating another example ofconstruction of a substrate processing apparatus used in carrying out asubstrate processing method according to the invention.

FIG. 5 is a schematic sectional view of the substrate processingapparatus illustrated in FIG. 4.

FIGS. 6A-6E are views for explaining operations in the substrateprocessing method according to this invention, and are plan views eachillustrating a substrate.

FIGS. 7A-7G are views for explaining the problem incidental to theconventional method of scan rinsing, and are each plan viewsillustrating a substrate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Several preferred embodiments according to the present invention arehereinafter described referring to the drawings.

FIGS. 1 and 2 illustrate one example of construction of a substrateprocessing apparatus used in carrying out a substrate processing methodaccording to the invention, and in which FIG. 1 is a schematic plan viewof the substrate processing apparatus, and FIG. 2 is a schematicsectional view.

In this substrate processing apparatus, cleaning (rinsing) is conductedafter a substrate on which surface a resist film having been exposed isformed. The substrate processing apparatus is provided with a spin chuck10 holding a substrate W in a horizontal posture, a spindle 12 to theupper end of which the spin chuck 10 is fixed and which is verticallysupported, and a rotation motor 14 of which rotary shaft is connected tothe spindle 12, and which causes the spin chuck 10 and the spindle 12 torotate about a vertical axis. A cup 16 is disposed around the spin chuck10 so as to surround the substrate W on the spin chuck 10. The cup 16 issupported in a manner of a reciprocating motion in a vertical directionby a support mechanism, not illustrated, and a drain tube 18 isconnected in communication to the bottom of the cup 16. Furthermore,although not illustrated in FIGS. 1 and 2, there is provided a mechanismfeeding a developer onto the substrate W, for example, a developer feedmechanism provided with a developer discharge nozzle on the lower endface of which a slit-like outlet is formed, and while a developer isbeing discharged from this slit-like outlet, the developer dischargenozzle is linearly moved in a horizontal direction orthogonal to theslit-like outlet, to feed and evenly spread the developer onto thesubstrate W, or a developer feed mechanism provided with a developerdischarge nozzle formed of a straight nozzle, this developer dischargenozzle is supported such that an outlet at a tip end is reciprocatedbetween a discharge position of being located right over the center ofthe substrate W and a stand-by position, and the developer is dischargedonto the center of the substrate W from the tip end outlet of thedeveloper discharge nozzle.

Moreover, a DI water discharge nozzle 20 discharging onto the substrateW a cleaning solution (rinse), for example, DI water is disposed in thelateral vicinity of the cup 16. The DI water discharge nozzle 20 ischannel-connected to a DI water supply source through a DI water feedtube 22, and a pump 24, a filter 26 and a switching control valve 28 areinterposed in the DI water feed tube 22. The DI water discharge nozzle20 is held by a nozzle holding portion 30 so as to be capable of turningwithin a horizontal plane, and turned within the horizontal plane by arotating drive mechanism 32. Furthermore, as illustrated by an arrow ain FIG. 1, the DI water discharge nozzle 20 is constructed so as to bescanned from a position where the outlet is opposed to the center of thesubstrate W to a position where the substrate W is opposed to acircumferential edge of the substrate W while discharging the DI waterfrom the outlet at the tip end to the surface of the substrate W, and asillustrated in the two-dot chain lines, so as to reciprocate between astand-by position of being out of place to the outside from the cup 16and a position where the outlet is located right over the center of thesubstrate W.

Furthermore, this substrate processing apparatus is provided with a gasjet nozzle 34 blowing out a gas, for example, a nitrogen gas from a jethole located at a tip end onto the substrate W, on the opposite side ofthe DI water discharge nozzle 20 with the cup 16 being sandwiched, inthe lateral vicinity of the cup 16. The gas jet nozzle 34 ischannel-connected to a nitrogen gas supply source through a gas feedtube 36, and a switching control valve 38 is interposed in the gas feedtube 36. The gas jet nozzle 34 is held by a nozzle holding portion so asto be capable of turning within the horizontal plane, and turned withinthe horizontal plane by a rotating drive mechanism 42. Further, the gasjet nozzle 34 is constructed so as to reciprocate between a stand-byposition being out of place to the outside from the cup 26 asillustrated in the two-dot chain line in FIG. 1, and a position wherethe jet hole is located right over the center of the substrate W asindicated by the solid line.

The switching control vale 38 interposed in the gas feed tube 36 isconnected to a controller 44. By this controller 44, the operation ofblowout and stop of the nitrogen gas from the jet hole of the gas jetnozzle 34 is controlled. That is, a switching operation of the switchingcontrol valve 38 is controlled by the controller 44 such thatimmediately after the DI water discharge nozzle 20 has just started tomove from the center of the substrate W to the periphery, and at thetime point when the outlet of the DI water discharge nozzle 20 moves asmall distance from a position opposed to the center of the substrate Wto have reached a predetermined position (position indicated by thesolid line in FIG. 1), the nitrogen gas is blown out from the jet holeof the gas jet nozzle 34 to the center surface, and thereafter thisblowout is stopped. More specifically, it is controlled such that the DIwater discharge nozzle 20 is started to move, and after a first driedcore is produced in a region inside of a circumference letting a centerposition of the substrate W be a center and letting a distance therefromto a position on the substrate opposed to the outlet of the DI waterdischarge nozzle 20 be a radius, before a second dried core is produced,the nitrogen gas is blown out from the jet hole of the gas jet nozzle34. At the time of the blowout of the nitrogen gas to the center surfaceof the substrate W, the nitrogen gas of a large flow rate may beinstantaneously blown out from the jet hole of the gas jet nozzle 34, orthe nitrogen gas of a small flow rate may be continuously blown out.

Using the substrate processing apparatus illustrated in FIGS. 1 and 2,after a developer is fed onto a resist film having been exposed formedon the surface of the substrate W to process the resist film, a DI wateris fed onto the substrate W while the substrate is being rotated at acomparatively low speed, to make cleaning so that the developer iswashed out and removed from on the resist film on the surface of thesubstrate W, and thereafter the substrate W is rotated at acomparatively high speed to make a spin-drying (scan rinsing). At thetime of scan rinsing, the substrate W that is held on the spin chuck 10is rotated at a comparatively high speed by the rotation motor 14, andwhile the DI water is being discharged from the outlet of the DI waterdischarge nozzle 20 onto the substrate W, the DI water discharge nozzle20 is scanned, and in this process, a nitrogen gas is blown out from thejet hole of the gas jet nozzle 34 toward the center surface of thesubstrate W.

Showing specifically one example with numerical values, a substrate W ofa diameter of 200 mm to 300 mm is rotated at a rotation speed of 1800rpm to 2100 rpm, thereby the DI water discharge nozzle 20 is moved to aposition where an outlet thereof is opposed to the center of thesubstrate W, and then the DI water discharge nozzle 20 is moved at ascan speed of 6 mm to 10 mm toward the periphery of the substrate W,while the DI water is being discharged at a flow rate of 0.41/min to0.61/min from the outlet of the DI water discharge nozzle 20 onto thesubstrate W. Then, after several seconds have elapsed, for example, twoseconds have elapsed from the time point at which the DI water dischargenozzle 20 has started to move, that is, when the outlet of the DI waterdischarge nozzle 20 is moved to a position by a distance of 12 mm to 20mm from the center of the substrate W, as illustrated with a solid linein FIG. 1, a nitrogen gas is fed through the gas feed tube 36 from anitrogen supply source to the gas jet nozzle 34 of which jet hole islocated right over the center of the substrate W, and the nitrogen gasis blown out from the jet hole of the gas jet nozzle 34 to the centersurface of the substrate W. This blowout of the nitrogen gas isconducted, for example, for about one second at a flow rate of about101/min. Alternatively, the blowout of the nitrogen gas may beconducted, for example, for several seconds at a flow rate of about0.11/min. Although the blowout of the nitrogen gas from the jet hole ofthe gas jet nozzle 34 is stopped shortly after a dried region has beenformed at the central portion of the substrate W, the nitrogen gas maybe blown out from the jet hole of the gas jet nozzle 34 for a while.

The timing of blowout of a nitrogen gas toward the center surface of thesubstrate W has preliminarily been determined by making tests on thevarious conditions including type, kind, size or surface state of thesubstrate W, rotation speed of the substrate W, discharge flow rate ofDI water from the outlet of the DI water discharge nozzle 20, scan speedof the DI water discharge nozzle 20 and the like, and observing whetheror not the second dried core is produced after the first dried core hasbeen produced in the vicinity of the center of the substrate W.

The DI water discharge nozzle 20 is continuously scanned even when thenitrogen gas is blown out from the jet hole of the gas jet nozzle 34.Then, the outlet of the DI water discharge nozzle 20 is scanned up to aposition opposed to the circumferential edge of the substrate W. Whenthe outlet of the DI water discharge nozzle 20 has reached the positionopposed to the circumferential edge of the substrate W, the switchingcontrol valve 28 that is interposed in the DI water feed tube 22 isclosed to stop the feed of the DI water to the DI water discharge nozzle20, thus the discharge of the DI water from the DI water dischargenozzle 20 is stopped, and the DI water discharge nozzle 20 is moved tothe stand-by position. Then, when drying of the substrate W is ended,the rotation of the substrate W is stopped.

It is preferable that the timing of blowing out a nitrogen gas from thejet hole of the gas jet nozzle 34 or stopping the blowout is controlledby a microcomputer on the basis of an operating program. Alternatively,it is preferable that the position of the DI water discharge nozzle 20is detected by an encoder, and with this detection signal, at the timepoint when the DI water discharge nozzle has reached a predeterminedposition, the nitrogen gas is blown out from the jet hole of the gas jetnozzle 34 . As an alternative, it is preferable that using a timer, atthe time point when a predetermined time period has elapsed from thetime point of starting to scan the DI water discharge nozzle 20, thenitrogen gas is blown out from the jet hole of the gas jet nozzle 34,and at the time point when a predetermined time period has elapsed fromthis blowout time point, the blowout of the nitrogen gas is stopped.

Incidentally, it is preferable that in the process of scanning theoutlet of the DI water discharge nozzle 20 to the position opposed tothe circumferential edge of the substrate W, the rotation speed of thesubstrate W is decreased. Specifically, such a control is made by thecontroller (not illustrated) so that at the time point when the outletof the DI water discharge nozzle 20 is moved a predetermined distance,for example, at the time point when it has reached a radius position of60 mm from the center of the substrate W, the rotation speed of thesubstrate W is decreased, for example, from the number of revolutions of1800 rpm through 1200 rpm, to the number of revolutions of 1000 rpmthrough 1200 rpm. The number of times of changing the rotation speed ofthe substrate W is not limited to once, and the rotation speed of thesubstrate W is decreased stepwise. As an alternative, it is preferableto be controlled such that as the outlet of the DI water dischargenozzle 20 comes close to the position opposed to the circumferentialedge of the substrate W, the rotation speed of the substrate W isdecreased by degrees, for example, linearly decreased.

When conducting the scan rinsing by the above-mentioned method, theproduction of not less than two dried cores in the vicinity of thecenter of the substrate W can be prevented. Then, one dried regionletting only one dried core produced in the vicinity of the center ofthe substrate W be a starting point spreads all over the substrate W todry the substrate W, so that there is no occurrence of remaining driedmarks of the DI water. Thus, by the above-mentioned method, theoccurrence of, e.g., development failure can be eliminated.

FIGS. 4 and 5 illustrate another construction example of a substrateprocessing apparatus used in carrying out the substrate processingmethod according to this invention, and in which FIG. 4 is a schematicplan view of the substrate processing apparatus, and FIG. 5 is aschematic sectional view thereof. In FIGS. 4 and 5, each memberdesignated with the same reference numerals as in FIGS. 1 and 2 has thesame function and action as those of the above-mentioned memberdescribed in FIGS. 1 and 2, and further descriptions thereof areomitted.

This substrate processing apparatus has a construction of controllingthe rotating drive mechanism 32 with the controller 44 to control theoperation of moving and stopping the DI water discharge nozzle 20. Thatis, by the controller 44, the rotating drive mechanism 32 is controlledsuch that in the process that the outlet of the DI water dischargenozzle 20 is scanned from the position of being opposed to the center ofthe substrate W to the position of being opposed to the circumferentialedge of the substrate W as indicated by the arrow a, after the outlet ofthe DI water discharge nozzle 20 has started to move from the positionof being opposed to the center of the substrate W (position indicated bythe two-dot chain line in FIG. 4), the DI water discharge nozzle 20 isonce stopped at the time point when the outlet of the DI water dischargenozzle 20 has moved to a predetermined position (position indicated by asolid line in FIG. 4), and thereafter the outlet of the DI waterdischarge nozzle 20 is moved toward the circumferential edge of thesubstrate W.

Using the substrate processing apparatus illustrated in FIGS. 4 and 5,after a developer is fed onto a resist film having been exposed formedon the surface of the substrate W to process the resist film, a DI wateris fed onto the substrate W while the substrate is being rotated at acomparatively low speed, to make cleaning so that the developer iswashed out and removed from on the resist film on the surface of thesubstrate W, and thereafter the substrate W is rotated at acomparatively high speed to make a spin-drying (scan rinsing). At thetime of scan rinsing, the substrate W that is held on the spin chuck 10is rotated at a comparatively high speed by the rotation motor 14, andwhile the DI water is being discharged from the outlet of the DI waterdischarge nozzle 20 onto the substrate W, the DI water discharge nozzle20 is scanned as follows.

Showing specifically one example with numerical values, a substrate W ofa diameter of 200 mm to 300 mm is rotated at a rotation speed of 1800rpm to 2100 rpm, thereby the DI water discharge nozzle 20 is moved to aposition where an outlet thereof is opposed to the center of thesubstrate W, and then the DI water discharge nozzle 20 is moved at ascan speed of 6 mm to 10 mm toward the periphery of the substrate W,while the DI water is being discharged at a flow rate of 0.41/min to0.61/min from the outlet of the DI water discharge nozzle 20 onto thesubstrate W. Then, when the outlet of the DI water discharge nozzle 20has moved up to the position of a distance of 20 mm to 25 mm from thecenter of the substrate, the DI water discharge nozzle 20 is oncestopped. This DI water discharge nozzle 20 is once stopped at the righttime after the outlet of DI water discharge nozzle 20 has started tomove from the position of being opposed to the center of the substrate Wand before the center portion of the substrate W starts to be dried.Furthermore, the position of the DI water discharge nozzle 20 being oncestopped is set on the condition that supposing a circumference lettingthe center position of the substrate W be a center and letting adistance therefrom to the position on the substrate surface opposed tothe outlet of the DI water discharge nozzle 20 having been once stoppedbe a radius, there is only one dried core, being a starting point ofdrying in a small region inside this circumference. This timing and theposition of the DI water discharge nozzle 20 being once stopped haspreliminarily been determined by making tests on the various conditionsincluding type, kind, size or surface state of the substrate W, rotationspeed of the substrate W, discharge flow rate of DI water from theoutlet of the DI water discharge nozzle 20, scan speed of the DI waterdischarge nozzle 20 and the like, and observing whether or not thesecond dried core is produced after the first dried core has beenproduced in the vicinity of the center of the substrate W.

After a predetermine time period, for example, a time period of about 10seconds has elapsed since the DI water discharge nozzle 20 being oncestopped, the DI water discharge nozzle 20 is moved again toward theperiphery of the substrate W. The timing of starting to move the DIwater discharge nozzle 20 again is to be on and after drying has startedin a small region inside the circumference letting the center positionof the substrate W be a center and letting a distance therefrom to theposition on the substrate surface opposed to the outlet of the DI waterdischarge nozzle 20 having been once stopped be a radius. Then, theoutlet of the DI water discharge nozzle 20 is scanned up to the positionopposed to the circumferential edge of the substrate W, and when theoutlet of the DI water discharge nozzle 20 has reached the positionopposed to the circumferential edge of the substrate W, the switchingcontrol valve 28 that is interposed in the DI water feed tube 22 isclosed to stop the feed of the DI water to the DI water discharge nozzle20. The discharge of the DI water from the DI water discharge nozzle 20is stopped, and the

DI water discharge nozzle 20 is moved to the stand-by position. Whendrying of the substrate W is ended, the rotation of the substrate W isstopped.

It is preferable that the timing of once stopping or starting to moveagain the DI water discharge nozzle 20 is controlled by a microcomputeron the basis of an operating program. Alternatively, it is preferablethat the position of the DI water discharge nozzle 20 is detected by anencoder, and with this detection signal, the DI water discharge nozzle20 is once stopped or started to move again. As an alternative, it ispreferable that using a timer, the DI water discharge nozzle 20 is oncestopped at the time point when a predetermined time period has elapsedfrom the time point of starting to scan the DI water discharge nozzle20, and the DI water discharge nozzle 20 is moved again toward theperiphery of the substrate W at the time point when a predetermined timeperiod has elapsed from the stop time point thereof.

Incidentally, it is preferable that in the process of moving again theDI water discharge nozzle 20 to scan the outlet of the DI waterdischarge nozzle 20 up to the position opposed to the circumferentialedge of the substrate W, the rotation speed of the substrate S isdecreased. Specifically, such a control is made by the controller (notillustrated) that at the time point when the outlet of the DI waterdischarge nozzle 20 is moved a predetermined distance, for example, atthe time point of having reached a radius position of 60 mm from thecenter of the substrate W, the rotation speed of the substrate W isdecreased, for example, from the number of revolutions of 1800 rpm to2100 rpm, to the number of revolutions of 1000 rpm to 1200 rpm. It ispreferable that the time of numbers of changing the rotation speed ofthe substrate W is not limited to once, but the rotation speed of thesubstrate W is decreased stepwise. As an alternative, it is preferablethat as the outlet of the DI water discharge nozzle 20 comes close tothe position opposed to the circumferential edge of the substrate W, therotation speed of the substrate W is decreased by degrees, for example,linearly decreased.

At the time of scan rinsing using the above-mentioned method, byproperly setting the position where the DI water discharge nozzle 20 isonce stopped, the area of the portion in a state of just before beingdried in the vicinity of the center of the substrate W is controlled,and thus the production of not less than two dried cores in the vicinityof the center of the substrate W can be prevented. Then, one driedregion letting only one dried core produced in the vicinity of thecenter of the substrate W be a starting point spreads all over thesubstrate W to dry the substrate W, so that there is no occurrence ofremaining dried marks of the DI water. Consequently, by theabove-mentioned method, the occurrence of, e.g., development failure canbe eliminated.

Now, another embodiment of the method of scan rinsing using thesubstrate processing apparatus illustrated in FIGS. 1 and 2 isdescribed.

As described above, after the outlet of the DI water discharge nozzle 20has started to move from the position opposed to the center of thesubstrate W toward the circumferential edge of a substrate W, asindicated by the solid line in FIG. 1, a nitrogen gas is fed through thegas feed tube 38 from a nitrogen supply source to the gas jet nozzle 34of which jet hole is located right over the center of the substrate W,and the nitrogen gas is blown out to the center surface of the substrateW from the jet hole of the gas jet nozzle 34. Thus, drying is rapidlystarted in a small region inside the circumference letting the centerposition of the substrate W be a center and letting a distance therefromto the position on the substrate surface opposed to the outlet of the DIwater discharge nozzle 20 having been once stopped be a radius. Then, inthe same manner as in the case of scan rinsing with the use of thesubstrate processing apparatus illustrated in FIGS. 4 and 5, therotating drive mechanism 32 is controlled by the controller 44. Asindicated by the arrow a, in the process that the outlet of the DI waterdischarge nozzle 20 is scanned from the position opposed to the centerof the substrate W to the position opposed to the circumferential edgeof the substrate W, after the outlet of the DI water discharge nozzle 20has started to move from the position opposed to the center of thesubstrate W (position indicated by a chain two-dashed line in FIG. 1),the DI water discharge nozzle 20 is once stopped at the time point whenthe outlet of the DI water discharge nozzle 20 is moved to apredetermined position (position indicated by the solid line in FIG. 1),and thereafter the outlet of the DI water discharge nozzle 20 is movedtoward the circumferential edge of the substrate W.

In this manner, when a nitrogen gas is blown out to the center surfaceof the substrate W from the jet hole of the gas jet nozzle 34, drying israpidly started in a small region inside the circumference letting thecenter position of the substrate W be a center and letting a distancetherefrom to the position on the substrate surface opposed to the outletof the DI water discharge nozzle 20 having been once stopped be aradius, so that a time period when the DI water discharge nozzle 20 isonce stopped can be made shorter, resulting in improvement inthroughput. Although the blowout of a nitrogen gas from the jet hole ofthe gas jet nozzle 34 may be stopped immediately after drying at thecenter portion of the substrate W has started, the nitrogen gas may beblown out from the jet hole of the gas jet nozzle 34 for a while.

Additionally, in the foregoing description about each of theembodiments, the invention is applied to the processing of scan rinsingof a substrate after a resist film having been exposed and formed on thesubstrate has been processed. The invention, however, is not limited tothe case of drying the substrate having been processed by scan rinsing,but can be widely applicable to the case of scan rinsing of a substratehaving a highly water-repellent surface, for example, the case ofcleaning (scrubber processing) with a cleaning solution the surface ofthe substrate or the case of cleaning and drying the substrate havingbeen immersed and exposed.

What is claimed is:
 1. A substrate processing apparatus comprising:substrate holding means for holding a substrate in a horizontal posture;substrate rotating means for rotating the substrate held by saidsubstrate holding means about a vertical axis; a discharge nozzle fordischarging a cleaning solution from an outlet to a surface of thesubstrate that is held by said substrate holding means and rotated bysaid substrate rotating means; cleaning solution feeding means forfeeding the cleaning solution to said discharge nozzle; and nozzlemoving means for scanning the outlet of said discharge nozzle from aposition opposed to a center of the substrate to a position opposed to acircumferential edge of the substrate while the cleaning solution isbeing discharged onto the surface of the substrate from said outlet; thesubstrate processing apparatus further comprising: a gas jet nozzle forblowing out a gas toward a center surface of the substrate from a jethole thereof in a state that the jet hole is stopped at a positionopposed to the center of the substrate; gas feeding means for feeding agas to said gas jet nozzle; and control means for controlling said gasfeeding means such that immediately after the outlet of said dischargenozzle has started to move from the position opposed to the center ofthe substrate toward the circumferential edge of the substrate, the gasis blown out toward the center surface of the substrate from the jethole of said gas jet nozzle.
 2. The substrate processing apparatusaccording to claim 1, wherein said control means controls said gasfeeding means such that a gas of a large flow rate is instantaneouslyblown out toward the center surface of the substrate from the jet holeof said gas jet nozzle.
 3. The substrate processing apparatus accordingto claim 1, wherein said control means controls said gas feeding meanssuch that a gas of a small flow rate is continuously blown out towardthe center surface of the substrate.
 4. The substrate processingapparatus according to claim 1, wherein said control means controls saidgas feeding means such that the outlet of said discharge nozzle startsto move from the position opposed to the center of the substrate towardthe circumferential edge of the substrate, no gas is blown onto thecenter of the substrate, and after that, in a region inside acircumference defined by a center position of the substrate as thecenter and by a distance to a position on the substrate surface opposedto the outlet of said discharge nozzle as a radius, starting at theformation of a dried core, a gas is blown out to the center surface ofthe substrate from a jet hole of a gas jet nozzle.
 5. The substrateprocessing apparatus according to claim 4, wherein said control meanscontrols said nozzle moving means and the substrate rotating means suchthat the rotation speed of the substrate is decreased during the processof scanning the outlet of the discharge nozzle to the position opposedto the circumferential edge of the substrate.
 6. A substrate processingapparatus comprising: substrate holding means for holding a substrate ina horizontal posture; substrate rotating means for rotating thesubstrate held by said substrate holding means about a vertical axis; adischarge nozzle for discharging a cleaning solution from an outlet to asurface of the substrate that is held by said substrate holding meansand rotated by said substrate rotating means; cleaning solution feedingmeans for feeding the cleaning solution to said discharge nozzle; andnozzle moving means for scanning the outlet of said discharge nozzlefrom a position opposed to a center of the substrate to a positionopposed to a circumferential edge of the substrate while the cleaningsolution is being discharged onto the surface of the substrate from saidoutlet; the substrate processing apparatus further comprising: controlmeans for controlling said nozzle moving means such that after theoutlet of said discharge nozzle has started to move from a positionopposed to a center of the substrate toward a circumferential edge ofthe substrate, before drying at the center portion of the substrate isstarted, wherein a center position of the substrate is a center andwherein a distance to a position on the substrate surface opposed to theoutlet of said discharge nozzle is a radius, the outlet of saiddischarge nozzle is once stopped, and after drying has started in asmall region the outlet of said discharge nozzle is moved again towardthe circumferential edge of the substrate.
 7. The substrate processingapparatus according to claim 6, further comprising: a gas jet nozzle forblowing out a drying gas from a jet hole to the center surface of thesubstrate that is held by said substrate holding means and rotated bysaid substrate rotating means; and gas feeding means for feeding adrying gas to said gas jet nozzle.
 8. The substrate processing apparatusaccording to claim 6, wherein said control means controls said nozzlemoving means such that the movement of the outlet of said dischargenozzle is once stopped after the outlet of said discharge nozzle hasstarted to move from the position opposed to the center of the substratetoward the circumferential edge of the substrate and before drying atthe center of the substrate is started, and the outlet of said dischargenozzle is moved again toward the circumferential edge of the substrateafter drying has started, by a centrifugal force causing the cleaningsolution, which the surface of the substrate is covered with, to flow ina region inside a circumference defined by the center of the substrateas the center and by a distance to a position on the substrate surfaceopposed to the outlet of said discharge nozzle as a radius .
 9. Asubstrate processing apparatus comprising: substrate holding means thatholds a substrate in a horizontal posture; substrate rotating means thatrotates the substrate held by said substrate holding means about avertical axis; a discharge nozzle that has an outlet from which acleaning solution is discharged; nozzle moving means that moves theoutlet of said discharge nozzle from a first position to a secondposition, the first position being opposed to a center of the substrate,the second position being opposed to a circumferential edge of thesubstrate; and a gas jet nozzle that blows out a gas toward a dried corewhich is formed at a center surface of the substrate during the movementof the outlet discharging the cleaning solution from the first positionto the second position.
 10. A substrate processing apparatus comprising:substrate holding means that holds a substrate in a horizontal posture;substrate rotating means that rotates the substrate held by saidsubstrate holding means about a vertical axis; a discharge nozzle thathas an outlet from which a cleaning solution is discharged; and nozzlemoving means that moves the outlet of said discharge nozzle from a firstposition to a second position, the first position being opposed to acenter of the substrate, the second position being opposed to acircumferential edge of the substrate, wherein said nozzle moving meansstops the movement of the outlet discharging the cleaning solution at athird position between the first position and the second position andthen starts to move the outlet from the third position to the secondposition after forming a dried core at a center surface of the substrateand then spreading the dried core over a region inside a circumference,wherein a center position of the substrate is a center, and wherein adistance to a position on the substrate surface opposed to the thirdposition is a radius.